Does the IPD concept deliver as required and expected, and if not, how can that be explained? This paper is a critical realist inspired methodology based on a combination of the inductive and deductive approaches used in case study research. IPD is based on relational contracting between multiple parties, in this case between the Owner, Contractor, MEP subcontractors and a group of Consulting engineers who share control of the project. At the core of the concept is shared risk and opportunities among the parties in the IPD contract. Our theoretical perspectives are based mainly on the Principal-Agent theory (PA), Transaction Cost theory (TC), and its related incentives. This paper reports on a study of the development of an existing public hospital that is constructing first a psychiatry and then a somatic building. The data collection in the paper is mainly in connection with the construction of the psychiatry building in 2018. Our findings show that IPD represents a game-changer in the behaviours and the organizing of AEC (Architect-Engineer-Construction) projects, ex-post IPD-contract. We identify examples of swapping occurring that require deep collaboration, which stems from changes in the commercial incentives. However, different individual incentives coupled with accompanying mindsets and opportunistic behaviour are still part of everyday life and are linked to people's past experiences, which can be understood as contextual conditions. In addition, the decision-making processes were not effective and characterized by revisiting previous decisions.

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